static const char* fill_vert_shader =
      "#ifdef NVGP_GL3\n"
      " uniform vec2 viewSize;\n"
      " in vec2 vertex;\n"
      " in vec2 tcoord;\n"
      " out vec2 ftcoord;\n"
      " out vec2 fpos;\n"
      "#else\n"
      " uniform vec2 viewSize;\n"
      " attribute vec2 vertex;\n"
      " attribute vec2 tcoord;\n"
      " varying vec2 ftcoord;\n"
      " varying vec2 fpos;\n"
      "#endif\n"
      "void main(void) {\n"
      " ftcoord = tcoord;\n"
      " fpos = vertex;\n"
      " gl_Position = vec4(2.0*vertex.x/viewSize.x - 1.0, 1.0 - 2.0*vertex.y/viewSize.y, 0, 1);\n"
      "}\n";
